This is a Chicago house. Clay with damage and missing cover and debris stuffed inside. I think it is a clean out for the sewer, it runs right along the property line between the 2 houses. I just want to confirm, I can’t think of it being anything else.
If it were for the sewer it would smell.
Whatever it is, I don’t think the rock is the approved cap.
It may be for the downspouts (if they drain below ground).
Absent any water and/or odor, I would guess that it may be abandoned.
AH! Rick the downspouts do go underground!! You may be right. It didn’t smell. and was not wet either.
OK, maybe it’s not abandoned. If the downspout drains get clogged or brokem it is often easier to discharge the downspouts above grade and abandon the drains.